Synthetic analogs for evaluating the influence of N–H⋯S hydrogen bonds on the formation of thioester in acetyl coenzyme a synthase

Abstract

A series of square planar methylnickel(II) complexes, (dppe)Ni(Me)(SAr) (dppe = 1,2-bis(diphenylphosphino)ethane); 2. Ar = phenyl; 3. Ar = pentafluorophenyl; 4. Ar = o-pivaloylaminophenyl; 5. Ar = p-pivaloylaminophenyl; (depe)Ni(Me)(SAr), (depe = 1,2-bis(diethylphosphino)ethane); 7. Ar = phenyl; 8. Ar = pentafluorophenyl; 9. Ar = o-pivaloylaminophenyl; 10. Ar = p-pivaloylaminophenyl), were synthesized via the reaction of (dppe)NiMe2(1) and (depe)NiMe2(6) with either the corresponding thiol or disulfide. These complexes were characterized by various spectroscopic methods including 31P NMR, 1H NMR, 13C NMR and infrared spectroscopies and in most cases by X-ray diffraction analyses. Solid state and solution measurements establish that 5 and 9 contain intramolecular N-H---S bonds. Carbonylation of the complexes 2-4, 7-10 leads to (dRpe)Ni(CO)2 and MeC(O)SAr via the intermediacy of the acylnickel adducts, (dRpe)Ni(C(O)Me)(SAr), detected at low temperature by 31P NMR spectroscopy. Consistent with experimental observations, density functional theory results reveal that the intramolecular hydrogen bond in 9 stabilizes the acylnickel adduct compared with its non-hydrogen-bonded adduct, 10. Oxidative addition of MeC(O)SC6F5 to (dRpe)Ni(COD) followed by spontaneous decarbonylation proceeds in modest yields generating 3 and 8.

Modelling strategies for the covalent functionalization of 2D phosphorene

“…11. Here, the optimized Ni–P distances of 2.24 Å are about 0.1 Å longer than those in the comparable X-ray structures formed by a diphosphine chelate,41 while the P 1 –Ni–P 2 angle of 95.2° is about 8° more open. These aspects are likely the consequence of the already known weaker donor power of the phosphorene P atoms and their strained geometry.…”

Exploring Regioselective Bond Cleavage and Cross‐Coupling Reactions using a Low‐Valent Nickel Complex

“…In addition,R iordan has reportedt hat the use of ac omparable nickel(0) complex led to the cleavage of the C acyl ÀSb ond of thioesters containing an electron-deficient C 6 F 5 substituent. [12] We recently reported the synthesis of 2-nickelaoxetanes, [13] prepared from the oxidativea ddition of [{(dtbpe)Ni} 2 (m-h 2 :h 2 -C 6 H 6 )] [14] (1)( dtbpe = 1,2-bis(di-tert-butyl)phosphinoethane) onto epoxidest hat bear aketone group. Our mechanisticstudies indicated that the precoordinationo ft he metal centre to the carbonyl of the epoxide was crucial for the reaction to occur.W et hus soughtt oe xplore what other transformations could be enabled by precoordinationo fareactive, low-valent nickel centre to ac arbonyl fragment of organic molecules.…”

“…Upon heating, CO is released and activation of a second equivalent of thioester led to a platinum dithiolate complex. In addition, Riordan has reported that the use of a comparable nickel(0) complex led to the cleavage of the C acyl −S bond of thioesters containing an electron‐deficient C 6 F 5 substituent …”

C–S Bond Activation of Thioesters Using Platinum(0)

“…PtÀCH 3 appeared in the 13 C{ 1 H} NMR spectrum as a doublet of doublets with platinum satellites at δ À4.96 (J PÀC = 7.7 Hz, J PÀC = 87. 6 Hz, J PtÀC = 534.5 Hz). In the 1 H NMR spectrum, the methyl resonance was obscured by overlap with the isopropyl resonances (confirmed by HSQC NMR spectroscopy).…”

“…In the 31 P{ 1 H} NMR spectrum, 8 appears as a singlet with platinum satellites at δ 66.25 ( 1 J PtÀP = 2747 Hz, 3 J PtÀP = 64. 6 Hz, 3 J PÀP-trans = 24.1 Hz, 3 J PÀP-cis = 8. 3 Hz).…”